The vacancy arose after Sir Paul Stephenson resigned amid media coverage over the phone hacking row and his acceptance of a free stay at a health resort while recovering from surgery.
The Mayor and Metropolitan Police Authority Chair Kit Malthouse were appearing before the Home Affairs Select Committee which is looking into the policing of the August riots and disorder.
Questioned about the system for appointing the Commissioner, Mr Johnson said told the committee it was a “vexed issue”.
By law the Home Secretary makes a final recommendation to the Queen having had “regard” to the views of the Mayor.
Despite this lack of formal input, Johnson claimed the need for any Commissioner to have the ongoing support of the Mayor gave him an “effective veto” over any appointment.
The Mayor told David Winnick that the death of Mark Duggan, which triggered the initial rioting in Tottenham, “did immediately strike me as being a potentially very difficult incident”.
Mr Johnson also said he returned from his holiday “once it was obvious that events were not coming down”.
Questioned about police tactics, Mr Malthouse said it was important for politicians to “allow the police to do their job” and “not to interfere in any way”.
The Mayor told MPs that Londoners have a “great deal of respect” for the Police and said while it was possible to criticise with “20:20 hindsight” the “crisis” had caught everyone unawares.
